10 - Parameters and Pointers

Question 1

How does one print the value of a decimal integer?

Answer 1

printf(“%d”,n) in C

push myint //push the value of the variable onto the stack
lea eax,format //address of the format string is saved in eax
push eax //push the address of the string to the stack
call printf //call printf, it will take two parameters from the stack
add esp,8 //clean top two positions in the stack

Question 2

How does one scan a decimal value ?

Answer 2

scanf(“%d”, &n)

&n is the address of the variable ‘n’

Question 3

What does %c do in printf?

Answer 3

Print a character

Question 4

What does %i do in printf?

Answer 4

Print a signed decimal number

Question 5

What does %s do in printf?

Answer 5

Print a string of characters

Question 6

What does %c do in scanf?

Answer 6

Read a single character

Question 7

What does %d do in scanf?

Answer 7

Read a signed decimal integer

Question 8

What does %s do in scanf?

Answer 8

Read a string of characters until a whitespace char (blank, newline, tab)

Question 9

What are the two types of jump instructions ?

Answer 9

• Conditional: JCXZ, JECXZ

- Unconditional: JMP <address></address>

Question 10

JC, JNC ?

Answer 10

JC = Jumps if carry flag is set (=1)

JNC = Jumps if carry flag is clear (=0)